[Linux-fbdev-devel] fb access

[Mayuresh D. <ma...@ya...>]

I have two questions:


1) i have a photocell connected on my screen which
tells me my refresh rate.
how can i send a signal from the parallel port maybe
that syncs with  the vertical refresh signal. How do i
know that it is exactly syncing. 

2) Suppose a have a switch. How do i flip frames (or
screens) using the fb device or in any other
appropiate way when i turn the switch on/off??


Thanks,
Mayuresh

**********************************************
Mayuresh Deorukhkar
Graduate Research Assistant
University Of Missouri - Columbia
**********************************************



On Wed, 6 Jun 2001, Deorukhkar, Mayuresh S.
(UMC-Student) wrote:

> Hi,
> 
> we are working on real time linux and we want to
know when a screen
refresh
> occurs.
> How do we detect a vertical refresh strobe??
> 

The right way to do it is via interrupt, however X is
completely in
userspace so you need to write a kernel driver to
catch this interrupt. 
At least as far as ATI cards are concerned it is
fairly easy to intruct
them to make this interrupt. Just be careful of dri
interactions - the
very same interrupt is used for everything else too.

                         Vladimir Dergachev

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